Line finder with differential test relay



Dec. l, 1953 w. 'n POWELL 2,661,396

LINE FINDER WITH DIFFERENTIAL TEST RELAY Original Filed July l0, 1947 l2 Sheets-Sheet 1 oOo T 2 LINE LINEAFINDER I #34 ("I CG OOLOOOOOOOO ATTORNEY Dec. 1, 1953 W. T. POWELL Original Filed July 10, 1947 12 Sheets-Sheet 2 T T R n S S LET LFT LFR LFR LI-'s \LFs \SYB ,95 IL I l 'mo Lr- LI- i?. I ,L .L .L SR II I+) Z sve I I 2 I I I 3 I I I I 3 SXB I I I I COMMON To LINE FINDER o I ALLoTTER ALG REL/:Ys C XB I I I I IN SAME LEVEL I I I I I I I IALG I zALs I 25ALG fsf 93 F I f ,-I1 I l 'QI- I rn I I 73 hr4 I I+I f L. I+I I TLLHI v LI- I L I LI.- +I IAL I 2A'- 25AL RM l To sELEcTon To sELEcToR xONl--I-I H', I "H rINnsRFz I+) FINDER 25 n :92 I L. F LO-(+) l l X ST xoN g REGISTER SENDER ALLoTTER q; 9,

+I-ll Fla 2 INI/ENTOR.

WINFRED T. POWELL ATTORNEY Dec. l, 1953 LINE FINDER W. T. POWELL WITH DIFFERENTIAL TEST RELAY 12 SheetIs-Sheet 3 I. n s

LFT

LFR

SELECTOR FINDER LFS SYB YB o9 L95 SF o o I I 94 RC' SFR E* I -L I I (-1 SFT Le l I I I I I SR SRoo I w l Il ;H 1ST Q o I l I kJ-w. I I I I *I SWO o I l I l I l I I I I l (-H V-@Yl' I C88 H m F fg I R Il \73 -l-M/V-H YsT /OPR fYON (-1 fOPT ,SW I SELECTOR ,92

I (+)-o-J-I \YoN 3 ST\ FIG. fQIi- SRL GRD\ PULSE IN PULSE OUT NVENTOR.

SS WINFRED T. POWELL ATTORNEY Dec. .1, 1953 W. T. POWELL Original Filed July l0, 1947 l2 Sheets-Sheet 4 T H T S S cT L I CR RLT E @43E-( 2- D IIII-I SELECTOR |xo- 89|| l \72I E l l ci I I S` of T WEI 71 l Lo-I+) I' FIG/3 I l FIG. FIG. FIG. FIG. FIG. FIG. I 1 2 3 4 5 e l FIG. FIG. 1 8 7 FIG. FIG. a8 I CHO IO 9 L||f`|j-m FIG. FIG. 12 II IIII xAoN ISELEcToR FIG.4

INVENTOR.

WINFRED T. POWELL ATTORNEY Dec. 1, 1953 w. T. POWELL LINE FINDER WITH DIFFERENTIAL TEST RELAY l2 Sheets-Sheet 5 Original Filed July 10, 1947 PICK uP STICK 2 STICK f CONNECTOR FIG. 5

NVENTOR. WINFRED T. POWELL ATTORNEY Dec. 1, 1953 w. T. POWELL 2,661,396

LINE FINDER WITH DIFFERENTIAL TEST RELAY Original Filed July 10, 1947 12 Sheets-Sheet 6 I C75 I MKII l I I I I I I -EII-I Ig-IH I STICK 2 l IIL" u :ULI-1, 1I STICKI l 'IL 'IL 1||`3l| I I T I L79 I Il Il I l TKO o o I I I l I I L69 I l I I R`o o o I I l f77 E Il Il I Soo o R 3N I ON |66- |16- 7a E] I III I TL; a-UP 4-IN I I L l I 76 R-Bo f I-Il I I 68 REV. RING TONE CONNECTOR FIG. 6

A INVENTOR. WINFRED T. POWELL Dec. 1, 1953 w. T. POWELL LINE FINDER WITH DIFFERENTIAL TEST RELAY Original Filed July l0, 1947 l2 Sheet s-Sheet '7 I/GRD SW OPT OPR SR ST INCOMING COUNTING RELAYS REGISTER SENDER FIG. 7;

oPR

INVENTOR. 'w/NFRED T. POWELL ATTORNEY Dec. 1, 1953 W. T. POWELL LINE FINDER WITH DIFFERENTIAL TESTl RELAY Original Filed July 10, 1947 l2 Sheets-Sheet 8 sTf INCOMING COUNTING RELAYS :t t I4 I4 I l sT1cK-2 IVnlVPlJ-U- IIL i VIT *II *II "II 1 @H @im im I I I I I I I' I' I' l I I I l I sT/cK1 (H4-Ii EI. i I I I l R-15 HL I l I #wir I I I r CRL :I ILP l l I I I l Y wm 1 l I I l I I I I I I I I I f6? FLL l ..41 l I I I;

l.-cHo l LA I DII. fCIOII Il C u TONE I I LI n+1- I l u i F/AG. 8

20T/11.0 /ZLD /fMG /ZMG /TF TIN INVENTOR.

WINFRED T. POWELL ATTORNEY Dec. l, 1953 w. T. POWELL 2,661,396

LINE FINDER WITH DIFFERENTIAL TEST RELAY Original Filed July 10, 1947 l2 Sheets-Sheet 9 OPH REG/STER SENDER 0PT\\ SW /A fa fC /D LD GRD [LD \D d2 H5 l I REG/STER TIT- u/vlTs REG/STER T-Iil STAT/olv REG/STERHL dMG I l I 57i-ihr] 4TF i 3TF El I F II I 3x I I I II r-TTI I -r IUI VTI* -r I I III I l III I I I l FII III VI| I I I9? I) I I I I I); l l I-II VIL I I' v I I I 'IIIIIII- I ISS I I I ITL l I l I I| l. I-I *I l i Eq-I I l I II sa (-I: {II- I I I l I I' I I I i I I u I I JL I VI- I I I I I I I I I I I I i I I I l @EH-1 l I I s s I I I A l Il I I I I I l 1 III? W/NFRED T. POWELL BY F/G. 9

HUNDREDS REGISTER W. T. POWELL LINE FINDER WITH DIFFERENTIAL TEST RELAY L zMG fTF REGISTER I ITHousA/vos WINFRED T. POWELL BY ATTORNEY 1|11|Hnm|wm|wmlnm|wm ||m :--M V2 M |LM| LL IW ,31

Dec. 1; 1953 w. T. POWELL LINE FINDER WITH DIFFERENTIAL TEST RELAY 12 Sheets-Sheet 1l Original Filed July 10, 1947 sLow oPERATE H4@- BA1 87 l 83 sw REGISTER SENDER f2me fel

PICK-UP STICK 2 l* STICK 1 IJ- INVENTOR.

WINFRED T. POWELL T, M ATTORNEY Dec. l, 1953 w. T. POWELL LINE FINDER WITH DIFFERENTIAL TESTl RELAY 12 Sheets-Sheet 12 Original Filed July l0, 1947 I \16 I9 |85 I I I I I I I I I I feel TLL [87 faz sw/aa ZMG | I IIJ.

CHO

OUTGOING COUNT/NG RELAYS INVENTOR. WINFRED T. POWELL B" CN ATTORNEY FIG. I2

Patented I Dec. 1, 17953 LINE FINDER WITH DIFFERENTIAL TEST RELAY Winfred T. Powell, Rochester, N. Y., assignor to Stromberg-Carlson Company, a corporation of New York Original application July 759,972. Divided and this 10, 1947, Serial No. application January 15, 1949, Serial N0. 71,152

Claims. (Cl. 179-18) The present invention concerns improvements in or relating to telephone systems and it more particularly pertains to automatic telephone systems.

The present application is a division of my co-pending application Serial No. 759,972, led July 10, 1947, now Patent No 2,541,936.

One object of the present invention relates to a register-sender type automatic telephone system, in which a comparatively few relay type registersenders are provided for controlling the various switching stages in the system. The switching equipment is preferably of the step-by-step switch type, known to the trade as XY switches.

Another object of the present invention relates to the use of relay type allotters for allotting links in advance of calling conditions on calling lines. Since there are comparatively few registersenders and comparatively few allotters in a large automatic telephone system, such as contemplatedby the present invention, and since it is usually required that the register senders and allotters be extremely fast and reliable in operation, these units of the present invention are made 'up of relays only.

Still a further object of the present invention is the provision of differentially controlled test relays in the line nder and selector nder circuits, .whereby these relays are quickly released to stop the finder operation on the marked line or trunk.

It is a still further object of the present invention to provide two sets of counting relays in each register-sender, one set for registering the impulses from the calling dial, the other set for registering the impulses transmitted from the register-sender to the switch train, with a correspondence or matching circuit arrangement interconnecting these two counting relay sets, whereby sending from the register-sender is stopped when the number of impulses transmitted therefrom corresponds to the number of impulses received therein from the calling dial.

Another object of the present invention relates to a by-pass arrangement, whereby the registersender is discharged after transmitting only one digit, instead of waiting for the transmission of four or ve digits representing the usual number of digits for selecting the called station. This arrangement is usually for clearing out a register-sender when a single digit number, 0 for toll, for example, is dialled into the register-sender.

Other objects, purposes and characteristic features of the present invention will be in part obvious from the accompanying drawings and in 2 part pointed out as the description thereof progresses.

In describing the invention in detail, reference will be made to the accompanying drawings in which like characters designate corresponding parts and in which Figs. 1 to 1'2, inclusive, when arranged in accordance with the diagram of Fig. 13 and with correspondingly identiied lines in alignment disclose a suicient amount of circuits for an understanding of the various features provided by the present invention.

For the purpose of simplifying the illustrations and facilitating the explanation, the various parts and circuits constituting the embodiment of the invention have been shown diagrammatically and certain conventional illustrations have been employed, the drawings having been made more with the purpose of making it easy to understand the principles and mode of operation than with the idea of illustrating the specic construction and arrangement of parts that would be employed in practice. For example, the various relays and their contacts are illustrated in a conventional manner, with all of the contacts associated with a particular relay being illustrated as controlled by this relay by means of a dashed line associating the relay coil and associated contacts. The negative side of the common exchange battery is indicated by a minus sign in parenthesis and the positive side of the same exchange battery, which is usually grounded, is indicated by a positive symbol in parenthesis.

It is believed that the invention will be best understood by explaining the operation of the various circuits when a call is originated from a particular calling line, for example line #34 shown in the upper left-hand corner of Fig 1, this call being directed to the wanted station by dialing a live-digit number,y these digits comprising a thousands or oiiice digit, a hundreds digit, a tens digit, a units digit and a station digit. For convenience in describing the various circuit operations, it will be assumed that the calling party dials #31111.

It will also be described how the circuits function when the calling subscriber dials a single digit, #0 for example, in the register for causing the iirst selector to advance to the O'level for selecting trunks to a toll board or the like.

When the receiver is removed at the calling station, line #34 for example, a circuit is closed for operating line relay LR of the line circuit, extending from break contact of cut-off relay CO, line and substation circuits in series, break contact of relay CO and winding of relay LR to Relay LR operates and, at-its upper break-make contact immediately applies (-1-) to the sleeve terminal S leading to the connector switch banks for making this line busy to incoming calls.

Relay LR also closes a circuit for operating the allotter group relay of the line finder allotter, which corresponds to the idle allotted link. It will be assumed that the line finder #l `of link #l is idle and allotted as marked by the associated allotter relays IAL and IALG being in their normal deenergized positions. The circuit for operating relay IALG extends from (.-1-), make contact of relay LR, common start conductor (common to all lines in the same 100 line group), break contact of allotter guard relay GD, break Contact of allotter relay IAL and winding of allotter group relay IALG to The operation of relay IALG (or any other ALG relay associated with any other link of this same group) closes a circuit from (-1-), make contact of the operated ALG relay and winding of relay GD to for operating the VGD relay. A vlocking circuit is `now established for relay IALG lwhich extends from 4(.-.1) on ,thecommon start conductor, make con- .tact of relay GD, break contactof relay IAL, make .contact and winding of relay IALG to Since the allotter group relay (IALG in this example) is operated the X start relay XST of the line finder is operated for causing the line y;

i'inder switch to operate in its primary or X direction. This circuit for relay XST extends from (.-1-), make contact of relay IALG, break contact ofthe XOR-normal contacts of the finder switch in its normal position and upper winding of relay XST to The operation of relay XST immediately closes a bridge path around the normally closed X off-normal contacts for maintaining this circuit to the XST relay after the line nder is operated from its normal position.

The operation of relay XST closes a selfinterrupting circuit for X magnet XM which extends from (-1-.), make contact of relay XST, break .contact and winding of magnet XM to This Vcircuit causes the X magnet to be intermittently operated for vdriving the finder switch brushes in their primary or X direction. This self-interrupting circuit for the X magnet is effective in the .present example Ato .drive the line finder 4switch to the third level, since ythis is the level Yin which the calling vline is located. When the X brush XB (which is operated only `during the X movement of the finder switch) reaches the marked level, `level `#3 in the present example, a circuit is closed from (-1-) -make contact of relay LR, marking conductor which is common to all lines in the third level, level #3 terminal and brush XB, make contact and lower winding of relay XST to This lenergizes the lower winding of relay XST in a direction opposite to the upper winding energization and thus quickly releases this relay. When relay XST is released, both its upper and lower windings are now open so that it cannot be again operated until vthe associated nderswitch is restored to normal and used again. The release of relay XST opens up the energizing circuit of magnet XM, thus stopping the switch at the marked level and preventing its further stepping in the X direction.

With the line finder being off-normal and with relay XST being released, a circuit is closed for operating the Y start relay YST which extends from (-1-), make contact of relay IALG, X 01T- normal contact XON in its off-normal position,

IAL and winding of relay IALG to break contact of relay XST, Y off-normal contact YON in its normal position and lower winding of relay YST to Relay YST immediately closes a bridge path across the YON contacts for locking Athis relay in its v`energized position during the Y stepping operation.

The Y magnet YM is now operated over a self- Vinterrupting circuit extending from (-1-), make contact of relay YS'I, break contact and winding ,of magnet YM to for advancing the line finder in its Y or secondary movement until it iinds the ymarked calling line.

`When the calling line is found, a circuit is closed from (-1-) .make contact of relay LR, terminaland Y brush YB, make contact and upper winding of relay 'YST to for differentially energizing relay YST and quickly releasing its armatures. The release of relay YST opens up the Y magnet circuit and both windings of the relay so that this relay-cannot be again energized until Ythis iinder is restored to normal and -used again.

Referring back to the operation of relay of the line finder allotter, a circuit is closed .for

;. operating the allotter group relay ofthe registersender allotter, the particular allotter group relay of this allotter being Moperated. as vdetermined by the register-sender which is idle and allotted. It will be assumed that the #l register-sendel.isidle and allotted, consequently the allotter relays ,IAL and IALG corresponding :13.0 .the #1 register-sender 4will be in their normaler Ycieenergired conditions. The operation of relay IALG of the line iinder allotter closes a circuit for operating relay IALG of the register-,sender Yallotter A.extending from (-1- make contact l,of relay IALG of the 'line nder allotter, registersender allotter conductor RSA, break contact of guard :relay GD of Athe register-sender vallotter, 4break .contact of relay Relay IALG of the register-sender vallotter closes an obvious circuit for operating relay GD, which in turn transfers the winding of relay IALG from its above described operating Acircuit to a'locking circuit, extending from conductor RSA,make contact of relay GD, break contact lof relay IAL, make contact and winding of relay IALG'to Relay IALG of the register-sender allotter closes a circuit for operating the X start relay XST of the .selector finder, this circuit extending from (-1-), make contact of relay IALG, vbreak contact of Xoff-normal springs XON of the selector finder fand lower winding of relay XST -to The operation of relay XST closes-a bridge circuit across the XON contacts for maintaining relay XST energized after the selector finder begins stepping in its X direction. Relay XST closes a circuit for operating the lX magnet of the selector nder extending from (-1-), .make contact of relay XST, conductor 9 I, break contact and winding of magnet XM to Magnet XM operates in a self-interrupted manner .for stepping the selector finder in its .primary or 'X direction until it reaches the level associated with the line finder-selector link in use on this call, as marked by a connection to (-1-) .on conductor SXB by way of a make contact lof ,relay `IALG of the line finder allotter. Since relay IALG of the line finder allotter has ymarked the #l line finder, it being assumed that this line finder is in the first level of the selector nder, then this circuit to on conductor SXBybeing connected to the first vlevel contact of brush XB of the ,selectornden when the selector finder .reaches the first level this circuit 'to (-1-;) is extended through brush XB, make contact and upper winding of relay XST to for differentially energizing this relay and causing it to release.

The release of relay XS'I opens up the circuit to the selector nder X magnet XM thus stopping the operation of this switch in its X direction. A circuit is now closed for operating the selector finder in its Y direction which extends from (-I-) make contact of relay IALG of the registersender allotter, X olf-normal make contact XON, break contact of relay XST, conductor 92, Y 01T- normal contact YON in its normally closed position and lower Winding of relay YST to Relay YST operates and closes a bridge circuit around this YON contact for maintaining this relay energized after the switch begins to step in its Y direction.

Relay YST closes an obvious circuit through the self-interrupting contact of Y magnet YM for automatically advancing the selector inder in its Y direction.

It will be assumed that the line nder selector nder link corresponds to the rst terminal in the first level of the selector finder. Consequently, When the selector lnder takes one X step (as previously described) and one Y step the upper winding of relay YST will be diierentially energized for releasing this relay over a circuit extending from make contact of relay IALG of the line inder allotter, conductor SYB, the rst terminal and Y brush YB of the selector finder, make contact and upper winding of relay YST to Since the line nder has found the calling line and since the selector nder has found the line nder-rst selector link, it is now in order to operate nder cut-in relay FCI of the line nder and register cut-in relay RCI of the selector nder. The circuits for operating these relays will be traced a little later. The operation of relay FCI extends the sleeve circuit of the rst selector back through the line nder to the cut-oir relay of the calling line and also opens up the release magnet RM circuit of the line nder for preventing the operation of this magnet until the connection is released. Relay FCI also operates the allotter relay of the line nder allotter for allotting the next line iinder-rst selector link for the next call. the allotter sender to the allotted line nder-rst selector link.

Referring back to the operation of relay IALG of the register-sender allotter, a preliminary or booster circuit is closed for operating calling bridge relay CB of the register-sender in advance of the extension of the calling line to the windings of this CB relay. This circuit may be traced from (-I-), resistor RII?, make Contact of relay IALG, sender ring conductor SR. extending from Fig. 2, through Figs. 3 and 7 to Fig. 8, and upper winding of relay CB to Relay CB closes an obvious circuit for operating slow acting relay SA and this relay closes a circuit for operating relay CX of the incoming counting relays, this circuit extending from make contact of relay SA, break contact of relay CRLP, conductor stick I, break contacts of counting relays CO to CI, inclusive and winding of relay CX to This prepares the incoming counting relays for receiving the rst digit transmittedY by the calling dial.

The circuit for operating relay FCI of the line finder and relay RCI of the selector finder may now be traced from make contact of re- The operation of relay RCI links t iinder may allotter opens up the above lay SA of the register-sender, conductor SS extending frorn Fig. 8 through Figs. '7 to Fig. 3, Y off-normal contact YON of the selector` finder, break contact of relay YST, upper winding of relay RCI, selector finder brush SFS and its associated contact, break contact of switching relay SW of the first selector, line iinder sleeve conductor LFS, Y off-normal contact YON of the line finder, break contact of relay 'YST and winding of relay FCI to Relay RCI connects its lower winding to the sleeve conductor SS leading down to the register-sender', thus completing a locking circuit for this relay.

Relay IAL of the line finder allotter is now operated over a circuit extending from (-1-), upper winding of relay IAL, make contact of relay FCI and resistor RIZ to Relay IAL closes a locking circuit for itself by way of its lower winding to (-I-) at the normally closed break contact of relay IiIAL and also to (-I) at the make contact of relay GD.

The operation of relay iAL opens up and releases relay IALG, which in turn opens up and releases relay GD, after which the next line be allotted since the circuit through the make contact of relay IAL to the next ALG relay is completed at a break contact of relay GD.

Relay IAL of the register-sender allotter is likewise operated over a circuit extending from (-I-), lower winding of this IAL relay, conductor 93, make contact of relay RCI and resistor RI! to The operation of relay IAL shortcircuits the upper Winding of relay RCI for excluding this winding from the sleeve circuit leading back to the calling line, it being understood that relay RCI now remains energized by way 01 its locking circuit including its lower winding. The operation of relay IAL of the register-sender allotter opens up and releases relay IALG, which in turn opens up and releases relay GD, thus completing the allotting circuit so that the next register sender can be allotted for the next call. rI'he release of relay I ALG of the register-sender described preliminary pulse circuit for relay CB of the sender, but this does not take place until after the calling line has been extended to the windings of this CB relay by way of the line finder and selector finder brushes as will be later described.

Both the line finder allotterand register sender allotter are arranged for rotating allotting feature, that is the allotting will take place from link to link until all links of the group have been allotted even though previously used links are dropped out before the allotting steps are completed all the way through. This is an advantage because it causes the links to be used in rotation, thus providing equal wear and tear. This is because the freeing or clearing out of a link does not release the associated AL relay for again allotting this link until all links have been used up to and including the last or the group, thus opening up at a break contact of the last AL relay the locking circuits for all previous AL relays, including their locking windings. It will be noted that the line nder allotter illustrates that there are l0 AL relays. This is because it is assumed that there are ten line nder-irst selector links in each 10G-line group. The register-sender allotter indicates that there are 25 AL and ALG relays vin the group. This is because it is assumed that 25 common register-senders are provided for serving all lines in a system of lOllil-line capacity.

-It has already been explained how'relaysCB, SA andA CX of the sender are operated in response tothe preliminary impulse applied to the CB relay when the register-sender allotter relayl IALG is operated. The calling line circuit is connected to the CB relay of theA registersender before relay EALG is released to open up this preliminary impulse circuit. The circuit for'energizing relay CB over the calling line may be traced from (-1-), lower Winding of relay CB, tip conductor ST, make contact oi relayl RCI, sender nder tip brush SFT and its associated contact, break contact of relay SW of the first selector, conductor I flFT, line finder brush LFT andits associated Contact, calling line and substation circuits in series, contact and associated line finder brush LFE, conductor LEFR, break contact of relay contact and associated selector nder brush SFR, make contact of relay RCI, ring conductor SR and upper winding of relay CB to With relay FCI o the line finder and relay RCI of the selector iinder operated a circuit is closed for operating cut-off relay CO of the calling line, which may be traced from (-1-), make contact of relay SA of the register-sender, sleeve conductor SS, Y oli-normal contact YON of the selector finder, break contact of relay YST, conductor ed., make contact of relay IAL of the register-sender allotter, conductor 95, brush SFS and. its associated contact of the selector finder, break contact of relay SW of the first selector, conductor LFS, Y off-normal contact YON of the line nnder, break contact ci relay make Contact of relay FCI, line finder brush 'LFS and its associated contact and winding of relay CO to The operation of relay CO opens up and releases relay LR and this latter relay switches the connector sleeve conductor S from direct (-1-) to (-1-) coming back over brush of the line finder by way of the circuit just described.

Referring back to the operation of relays CB, SA and CX of the register-sender, changeover relay CHO is operated in advance of the dialing operation, in order to give it a preliminary soak before intermittently energizing its winding. The circuit for operating relay CHO extends from (-1-), make contact of relay SA, break contact of relay CRLP, make contact of relay CX and winding of relay CHO to A circuit is now closed for operating the counting release relay CRL which extends-from (-1-), make contact of relay SA, winding of relay CRL, make contact oi relay CHO and resistor Riti` to Relay CRL operates and closes` a circuit for operating its repeater relay CRLP by extending its own operating circuit from (-1-) to the winding of relay CRLP.

Dial tone is now connected to the calling line to indicate that dialing may proceed. This circuit may be traced from the common dial tone conductor, condenser Cl, make contact of relay CRLP, make contact of relay CX, conductor IDT, break contact of relay ITE', conductor EDT tothe right-hand terminal of the lower winding ofV relay CB which is connected to the calling station over the above described circuit.

Since it was assumed that the rst dig-it is #3, three impulses are transmitted over the line for intermittently releasingr relay CB. During the time that relay CB is released and relay SA is de-energized, this latter relay maintains its armatures attracted until the next operation of the CB relay by reason vof its slow acting character- 3,1 istics. The` rst release of relay ClrI closes a circuit for operating the' :4:1z` counting relay which may betraced from (-1-), break contact of' relayv CB, make contact of relay SA, pick-up conductor,l make contact ofv relay CX and winding of relay CI toA The operation of relay CI opens@ up the above'described operating circuit for relay.- CX including conductor stick I, but relay CX is not released at this timeV because of a locking circuit' extending from (-1-), make contact of relay SA', break contact ofv relay CB, conductor stick 2, make contact and winding off relay CX to When relay CB is energized at the'end ofthe'l first impulse, thislstick 2 conductor is cie-eneri gized for releasing relay CX.

When relay CB-releases at the'beginningv of the secondv impulse, a circuitis closed for operating relay C2 whichextends by way of the pick-up conductor, break contact of relay CX, make contact of relay CI and winding of relay C2 to operated, as previously described, it was stick` I, this conductor being extended' b'ack` to the make contact of relay SA by way of the upper make Contact of relay- CRL in multiple withT the upper break contact ofrelay CRLP. When relay C2 operates,A this stick I conductor is switched from relay CI to relay C2, but relay CI does not release at this time because relay CB is cle-energized for extending (-1-) toconductor stick 2l andy up conductor by way of break contacts of relays CX and-CI anda make contact of' relay C2 tothe winding of relay C3Yfor operating this latter relay. Relay C3 transfersv the stick I conductor from relay C2: to relay C3- forlocking this latter relay f j, operated; Relay G21 does not release at this time becauseI relay CB isV released for applying (-1) to conductor stick 2 which is extended through breakv contacts-of relays CX and CI and a make contact of relay C2 to the winding of this latter relay.

When relay CBis energized at the end of the third impulse, (-1-) is removed from` conductor stick 2 for releasing relay C2. This leaves relay C3 operated as a result of the transmission of three impulses to the incoming counting relay circuit.

The intermittent release of relay CB during the transmission of impulses extends a circuit from (-1-), make contact of relay SA, break contact of relay CB, make Contact and winding of relay CHO to for maintaining this relay energized over its locking circuit. At the end of the series ofimpulses, relay CB remains energized sufficiently long to measure. o a period of time which isl longer than the slow acting release time of relay CHO, therefore, this latter relay is released toI mark the end of the transmission of the first digit.

When relay CHO is released to mark the end of the first digit, the relay or relays of the first digitregister may be operated to record and store the number of impulses dialed for this digit. In thev present example, #3 was dialed for the rst digit, consequently relay IC of the iirst or thousands register is operated over a circuit extendingfrom.

When relay C-I was"- locked. in its operated condition to (-1-) on conductor' (-1-) make contact of Vrelay SA, winding of counting release relay CRL, break contact of relay CHO, make contact of relay CRL, make contact of relay C3, (left operated in response to #3 being dialed), conductor C, break contacts in series of transfer relays TF to I'I'F, inclusive and winding of relay IC to Since this circuit extends through the Winding and make contact of relay CRL, this relay remains energized after the release of relay CHO by way of this locking circuit. Relay IC (or any other relay of the rst register `which may be operated in response to the rst digit) is locked over a circuit extending from (-1-), make contact of relay SA, make contact of relay CRLP, conductor TF, break contact of relay ITF, break contacts in multiple of relays 2X and 2TF, make contact and winding of relay IC to This circuit for locking relay IC may be traced back to the left-hand terminal of relay CRL from the Winding of relay IC, break contacts in series of relays ITF to 5TF, inclusive, conductor C, make contact of relay C3, make contact of relay CRL and break contact of relay CHO to the winding of relay CRL.

Since the other terminal of relay CRL is connected to at another make Contact of relay SA, relay CRL is short-circuited and released for in turn opening up and releasing relay CRLP.

`During the interval between the release of relay CRL and the release of relay CRLP, the counting relay left operated (in this example relay C3) is released because the stick I conductor is opened at a make contact of relay CRL and a break contact of relay CRLP. When relay CRLP releases, conductor stick I is again connected to (-1-) for again energizing relay CX to prepare the incoming counting relay circuit for the next digit. The

v'release of relay CRLP also closes a circuit for operating the first transfer relay ITF extending from (-1-), make contact of relay SA, conductor IMG, Winding of relay ITF, break contacts in multiple of relays 2X and 2TF, make contact and winding of relay IC to The operation of relay ITF transfers the four conductors `A, B, C and D from the relays of the first register to the relays of the second or hundreds register, comprising relays 2A, 2B, 2C and 2D.

With relay CX operated, relays CHO, CRL and CRLP are again operated in sequency over the previously described circuits.

It will be convenient to explain the complete operation of registering the digits dialed into the register-sender and thereafter referring back for an explanation of how the register-sender functions to re-transmit these digits out through the automatic switches. Relay CB is released once in response to dialing #l for the second digit, it being understood that this CB relay does not remain in its released position during the transmission of all digits long enough to permit relay SA to release. Consequently, relay SA remains operated until released after the re-transinission .has'been eifected, as will be later described.

The release of relay CB again closes the above described circuit for operating counting relay CI and for locking relay CHO in its operated position. The operation of relay -CB at the end of the single impulse transmission is effective to release relay CX and, since this is the end of the second digit, relay CHO will be released.

- Relay 2A of the hundreds register is now operated to register the second digit, which in this case is #1, the circuit being traced from (1-), make contact of relay SA, winding of relay CRL, break contact of relay CHO, make contact of relay CRL, make contact of the counting relay left operated in response to the second digit (in this example relay CI), conductor A, break contacts in series of relays 5TF to 2TF inclusive, make contact of relay ITF and Winding of relay 2A to The above described locking circuit for relay CRL is thus again completed. Relay 2A closes a locking circuit for itself which extends from (+L make contact of relay SA, make contact of relay CRLP, conductor TF, make contact of relay ITF, break contact of relay 2TF, break contacts in multiple of relays 3X and 3TF, make contact and Winding of relay 2A to The operation of the relay of the hundreds register extends its locking circuit back over conductor A to the left-hand terminal of relay CRL for releasing this relay and in turn releasing relay CRLP, in the previously described manner. During the interval between the release of relay CRL and the release of relay CRLP the counting relay left operated (in this example relay CI) is released because (-1-) is removed from conductor stick I. When relay CRLP is released, relay CX is again operated for preparing the incoming counting relay circuit for the third digit. The release of relay CRLP closes a circuit for operating relay ZTF which may be traced from (-1-), make contact of relay SA, conductor IMG, winding of relay 2TF, break contacts in multiple of relays 3X and 3TF, make contact and Winding of relay 2A to The operation of relay ZTF transfers the four conductors A, B, C and D from the hundreds register to the tens register.

The operation of relay CX again completes the circuit for eiecting the operation of relay CHO after which relays CRL and CRLP are again operated all in the previously described manner.

When relay CB is released for transmitting the third or tens digit, relay CI is again operated and relay CHO is again locked operated. When relay CBy is operated at the end of this impulse, relay CX is released and, since this is the end of the impulse transmission for the third digit, relay CHO is released.

The release of relay CHO again closes the above circuit for locking relay CRL and for operating the tens register relay (in this example relay 3A) because relay CI is operated for selecting conductor A which extends through break contacts of relays STF, 4TF and STF, conductor 96, and a make contact of relay 2TF and conductor 91 to relay 3A. Relay 3A operates and closes a locking circuit for itself which includes break contacts in multiple of relays 4TF and 4X and conductor TF in a manner previously explained. The closure of the locking circuit for relay 3A is effective to short-circuit and release relay CRL, after which relay CRLP is released, in a manner which will be understood from the previous explanation. During the interval between the release of relay CRL and release of relay CRLP, the counting relay left operated (in this example relay CI) is released. When relay CRLP is released, relay CX is again operated to prepare the incoming counting relay circuit for the units or fourth digit. Relay STF is now operated over a circuit which may be traced from (-1-) make contact of relay SA, conductor IMG, winding of relay STF, break contacts in multiple of relays 4TF and 4X, make contact and winding of relay 3A to The operation of relay CX is again effective to operate l l lrelay CHO which in turn effects the operations of relays CRL and CRLP-in sequence.

When relay CB is released in response to the impulse of the fourth digit, relay CI is again operated and relay CHO'is again locked operated. The operation of relay CBl at the end of this impulse is effective to release relay CX and, since this is the end of the impulse transmission for this digit, relay CHO is released.

Relay 4A of the units register is now operated and relay CRL is lockedv operated over a circuit from make contact of relay SA, winding of relay CRL, break contact of-` relay CHO, make contact of relay CRL, make contact of relayl CI, conductor A, break contact of relay 5TF, break contact of relay TF, make contact of relay STF and winding of relay 4A to Relay 4A is locked operated by way of its make contact, break contacts in multiple of relays ETF and 5X, break contact of relay TF, makecontacts in series of relays BTF, 2TF and ITF, conductor TF, make contact of relay CRLP and1make-contact of relay SA to (-I-). This locking circuit for the relay of the units register is extended back over the previously described operating circuit for this relay, including conductor` A for short-circuiting and releasing relay CRL. The releasev of relay CRL effects the release. of relay CI' after which relay CRLP is released. Relay CX isnow again operated to prepare the incoming counting relay circuit for the iifth or station digit. Relay CX again closes the above described circuit for operating relay CHO after which relays CRL and CRLP are again operated, asI previously explained. Relay' ATF is now operated for transferring the. four conductors A, B', Cand D from theY units register to the station register. This. circuit for operating relay: 4TF may be traced from (l) make contact of relay SA, conductor` IMG, winding of` relay IITF, break contacts in multiple of rela-ys FTF and 5X, make contact and winding of relay 4Ak to When the fifth, digit is dialed, relay CB' is again released for operating relay CI and for locking relay of this impulse, which is the end. of the digit, relay CX is released and thev locking circuit for relay CHO is opened for eiecting the release of this latter relay. Relay CRL is lockedA operated and relay 5A is operated over a circuiti which may be traced from (--l), make contact. of relay SA,winding of relay CRL, break contact of relay CHOmake Contact of relay CRL, make contact of. relay CI, conductor A, break contact of relay ETF, make contact of relay llTF and winding of relay 5A to Relay 5A closes a locking circuit for itself which may be traced from (JV), make contact of relay SAmake contact of relay CRLP, conductor TF, makecontacts of relays LTF to tlTF'inclusive, break contact of relay STF', conductor I6, break contact of. relay 6X, conductor I5, make contact and winding of relay 5A to- This locking circuit for thev relay of the station register is extended back over conductor A andthe make contacts of relaysk CI and CRL for short-circuiting and releasingv this latter relay. The releaseA oiV relayv CRL` effects the release of relays CI and CRLP ini sequence. A circuit is now closed for operating relayy ETF extending. from (-I-), make contact of relay SA', conductor IMG, winding of relay 5TH', make contact and winding of relay 5A to .l Relays CX, CHO, CRL and CRLP are again operated over their previously described circuits, but since CHO. When relay CB operates at the end l2 this is the last digit the operation of these: relays at this time is of no consequence.

It will be recalled that dial tone was applied to the calling line when the reg-ister-sender'was First seized, over make contacts of relays CRLP and CX and by way of a break contact of relay ITF. Since relay CX is released at the beginning of the transmission of the first seriesA of impulses, dial tone is disconnected from; the calling line at this point. However, relays' CX and CRLP operate betweeneach pair of digits and it becomes necessary to open up the dial tone circuit at another point to prevent'A reapplication of the dial tone to the calling' line between digits. Thisis done at the upper-most break contact of relay ITF, this relay being' opera-ted' at the end of the first digit' to permanently open the dial tone connection during this. call before relays CX and CRLP are operated to connect the dial tone circuit tothe calling line.

This completes the operation eiected in response to the dialing of the ve digits. It. will now be explained how the circuits function to retransmit the proper impulses outwardl from the register-sender tothe automatic switches;

Relay PO of the register-sender is a polarized type relay, with its contacts` remaining in the last position to which they are actuated, bythe energization of` a winding of the relay; In other words, they are not restored from their last actuated positions until the next energizati'on of the relay winding in an opposite direction. It; will now be explained how this-relay is intermittently operated for swinging its contacts toA the: right and left-hand'` positions at a rate which is proper for impulse transmission, for example,l 1:0 operations per secondi. It may bethatthis'polar` relay leaves its contacts in their right-hand. positions from a previous call,l inwhich caseit isl necessary to swing them over to. the; left. beforeimpulse transmission isstarted. This isidonev by; energiziing its lowerA winding in the direction of the arrow over a circuit extending from (+L make contact of.v relay RCI of the selectorv nd'er, con. ductor GRD', resistor R3, lower winding: or'. relay P02 and resistor RI to Since; relay RCI' is operated well in advance of the* conditioning: of

.the circuits for impulse transmission. by relay PO, this preliminary energization of the lower winding of this relay is effective to swing. its con.- tacts to the left in plentyof time to. get the circuit'k prepared fork impulse transmission.

Off-normal relayv ON of the register-sender is operated after the. rst digit istransmtted from the dial and the first transfer relay ITF is oper'- ated. The circuitfor operating'relay ON extends from (I+) make contact of relayV SA of the register-sender, conductor ZMG, make contact of relay ITF, conductor 98, and winding of relay ON' to Relay ON' closes a locking circuit for itself to on conductor ZMG, which is independent of the make contact of relay ITF. Relay ON applies to conductor GRD to maintain this conductor grounded independent of the make contact of relay RCI. Relay ON extends a connection from (-l) by way of a contact of relay PO in its left-hand position and resistor R'I to Thisapplies potential to the left-hand terminals of both windings of relay PO, current in this circuit divides, part. of it flowingthrough resistor R'I to and part flowing through' theA lower winding of relay PO and resistor R2 to Suicient current flows through the lower winding of' relay PO inthe direction opposite to theI arrow for swinging' its rnected to (-1-) `winding is reduced to zero, while 13 'contacts to the right. It will be noted that, before the contacts leave their left-hand positions,

the same potential is connected to bothA termi-- nals of the upper winding, that to the left-hand terminal being through a contact of relay PO in its left-hand position and that to the right-hand terminal of the upper winding being traced through a make contact of relay ON and condenser CN to conductor GRD, which is con- When relay PO swings its armatures to the right, the circuit to connected to resistor RI is opened and a circuit is now completed from (I) on conductor GRD, condenser CN, make contact of relay ON, upper winding of relay PO and resistor RI to This causes condenser CN to be charged, with the charging current flowing through the upper winding of relay PO and dividing and returning through the lower winding of relay PO to through resistor R2. This current is in such a direction (opposite to the arrows in both windings) as to hold the contacts of relay PO in their right-hand positions. When the charging current through the upper winding of relay PO drops below a certain value (as the condenser becomes charged) the current ilowing in this at this time current from (-I-) on conductor GRD ows through resistor R3, the lower winding of relay PO and resistor RI in the direction of the arrow associated with the lower winding of this relay for swinging its contacts to the left.

When relay PO has moved its contacts to the left, (-I) potential is again connected to the junction point between the left-hand terminals lof both windings of relay PO and resistor RI.

Condenser CN will then discharge through the upper winding of relay PO, causing current to flow through this winding in the proper direction for holding the contacts in their left-hand positions. Current is furthermore reversed through the lower winding of relay PO (with its contacts in its left-hand position) flowing through resistor R2 to This tends to swing the contacts of relay PO to the right, but cannot ai'ect this `operation until the condenser discharge current through the upper winding drops below a certain value. At the time that this condenser current drops below this certain value, relay PO swings its contacts to the right. This intermit- .g tent operation of relay PO for swinging its contacts back and forth continues until the circuit is cleared out as will be later explained.

Before proceeding with the explanation of the operation of the ICB, ISA and counting relays of g -the outgoing counting relay group in response to the operation of relay PO as just described, reference will be made to the closure of the conductors of the trunk circuit leading to the first selector for operating relays CB and SA of this:

selector in preparation for the receipt of impulses transmitted from the register-sender. lltfhen relay RCI of the selector nder is operated as previously explained, a circuit is closed for operating relay CB of the first selector which may be traced from upper winding of relay CB, break contact of relay CT, terminal and brush IST or the selector nder, make contact of relay RCI, conductor OPT, break Contact of relay IY of the register-sender, resistor R5, conductor GPR, make contact of relay RCI, brush ISR and its associated contact, break contact of relay CT and lower winding of relay CB- to Relay CB operates and closes a circuit for operating relay SA of the rst selector, this circuit extendlto the left and another 14 ing from break contact of relay CT, make contact of relay CB and winding of relay SA yto Referring back to the register-sender, the operation of relay ON swings the contacts of relay PO to the right, as previously described, and at the same time a circuit is closed from make contact of relay ON, contact of relay PO in its left-hand position, break contact of relay ICHO, break Contact of relay IY and wind- 'ing of relay IX to Since the circuits to relay IX and to the winding of relay PO for `swinging this latter relay to the right are closed at the saine time, relay IX will not operate because of its slow operate characteristics, since -the above described circuit to its winding is im- Imediately opened.

The circuit is now closed for operating relay ICB which extends from break contact of relay ICHO, make contact or" relay ON, break Acontact of relay I Y and winding of relay ICB to Relay ICB closes an obvious circuit for operating relay ISA and relay ISA closes a circuit for operating relay ICX of the outgoing counting relay group extending from (-4-) on master ground conductor 2MG, break contact of relay CHOP, make contact of relay ISA, stick I conductor, break contacts in series of relays ICII to ICI inclusive, and winding of relay ICX to When relay PO next swings its contacts to the left a circuit is closed for operating relay IX which extends from make contact of relay ON, contact of relay PO in its left-hand position, break contact of relay ICHO, break contact of relay IY and winding of relay IX to Relay IX has time to operate this time and when relay PO is next swung to the right a circuit is closed for operating relay IY and locking relay IX which extends from (-I-), break contact of relay ICHO,' make contact of relay ON, winding of relay IY, make contact and Winding of relay IX to The operation of relay IY opens up and releases relay ICB, this latter relay closing a circuit for operating counting relay ICI, which extends from break contact of relay ICB, make contact of relay ISA, pick-up conductor, make contact of relay I CX and winding of relay ICI to Relay ICI switches the stick I conductor from relay I CX to the Winding of relay I CI for closing a locking circuit for this latter relay and for opening up the previously described operating circuit for relay ICX. Relay I CX does not release at this time, however, because of another locking circuit extending from on conductor 2MG, break contact of relay CHOP,'make contact of relay ISA, break contact of relay ICB, conductor stick 2, make contact and winding of relay ICX to When relay PO next swings to the left, a circuit is closed 4for operating relay ICB which eX- tends from (-I-), make contact of relay ON, contact of relay PO in its left-hand position, break make contact of relay ICB to The oper- ICB opens up the above described locking 'circuit for relay ICX including conductor stick 2, thus eiecting the release of this latter relay.

It will be noted that relay PO is allowed to make one swing from its left-hand position to its right-hand position, followed by another swing swing to the right before the trunk circuit leading to the first selector is opened. This is because relay IY maintains a IY and winding of relay agee 13396 l closure across conductors OPT andV OPR. during these rst swings of relay PO. This' is to permit relay PO to settle down and attain a constant rate of cycling before'it is connected tothe trunk circuit.

With relay PO swung to the left, after relay IY is operated, the circuit to the first selector is opened for providing the rst impulses of the series. When relay PO next swingsl to the right, the trunk circuit is closed for marking the end of the first impulse of the series'. This swing of relay PO to the right also opens up the circuit to relay ICB for effecting the release of this latter relay. The release of relay ICB closes a circuit for operating counting` relay IC2 extending from (-l-, break contact of relay ICB, make contact of relay ISA, pick-up conductor, break contact of relay ICX, make contact of relay ICI and winding of relay IC2 to Relay ICI is preventedA from releasing at this time by means of a connection to (-I-) on conductor stick 2 as previously described.

When relay PO next swings to the left to mark the 'beginning of the second impulse the trunk to the fir-st selector is opened andV relay ICB is operated over the previously described circuit including a make contact of relay IY.

When relay PO next swings to the right' to mark the end of the second impulse, relay ICB is again released for closing a circuit for operating counting relay ICS, which circuit includes the pick-up conductor, break contacts of relays ICX and. ICI inseries, makecontact of relay IC2 and winding of relay Z'Clto- Relay ICI was re leased bythe operation of relay ICBat the beginning of the second. impulse because conductor stick 2 istie-energized. The swing of relay PO to the right closesit'he trunk circuit leading t'o the first selector to mark the endy of the second impulse.`

When relay PO next swings to the left, relay ICB' is again operated for effecting the release of'. relayA ICZ by de-energizing conductor stickv 2. This swing of relay'PO to the left marks the beginning of the third impulse by openin'g'the trunk conductors;

When relay PIO. next swings' to the right, relay ICB: is released andthe trunk conductors are closed for markingthe end' of the third impulse. Relay IC4? is operated at this time because relay ICB energizes the pick-up conductor'and relay ICE-f is locked at this timebecause relay ICB energizes the stick 2 conductor.

During the intermittent operations of relay ICB the circuit to relay' ISA is. interrupted, but this latter relay does not release because of its slow acting characteristics. It will now be explained how, even though. relay PO continues to operate intermittently, relay CB remains down long enough to effect the release of relayA ISA for marking the end of the transmission of the rst digit.

It will be observed thaty with relay IY operated, relay PO pulses the outgoing trunk circuit by swinging its uppermost contact to the left for opening this trunk circuit and swinging this contact to the right for closing the trunk circuit. As previously mentioned, relay PO keeps right on swinging therefore, it is necessary to close the trunk circuit after the required number of pulses are sentlout from the register-sender and keep this trunk circuit closed long enough to permit the selector switch to complete its trunk huntingI operation. This is donev by releasing -relay IY and thus bridging the pulsing contacts of relay PO when the proper number of pulses are sent, in this example three for the first7 digit.

Since relay IC of they thousands register was left operated in response to the registration of #3 for the first digit, a correspondence condition exists between the thousands register and the outgoing counting relay combination when three pulses have been transmitted over the trunk cir.- cuit. When relay PO swings to the right to close the trunk circuit to mark the end of the third pulse and relay ICII is operated' at this point in the cycle', a circuit is closed for operating changeover relay ICI-IO extending from on the master ground conductor ZMG, break contacts in series of counting relaysv ICII to ICE inclusive, make contact of relay ICA, channel conductor CH3, break contact of relay ID of the thousands register, make contact of relay IC, break contact of relay IB, break contact of relay IA, make-con"- tact of relay ITF, conductor I I, break contact of relay CHOP and winding of relay ICI-IO to The operation of relay ICHO closes a locking circuit for itself extending from (-i) on conductor ZMG, make contact of relay ITF, conductor 93, make contact of relay ICHO, break contact of relay CHOP and winding of relay SCHO to The operation of relay ICHO opens up the circuit leading to relays IX, IY and ICB, thus'releasing relays IX and IY and preventing the operation of relay ICB until a comparatively y.ong time interval has been measured off.' The release of relay IY closes the trunk circuit for the purpose above mentioned before relayl PO swings to the left to open this trunk circuit.

With relay ICB released, relay ISA releases after a time interval measured ofi by its slow acting characteristics for disconnecting (-l-l from the conductors stick I, stick 2 and pick-up of the outgoing counting relays, thus effecting the release of the relays of this counting relay group which were left operated (in this example relays IC3 and ICII). This restores all of the outgoing counting relays to normal and com'- pletes a circuit for operating relay CHOP which extends from (-I) on conductor EMG, break contacts in series of all counting relays, conductor 8l, make contact of relay ICHO and Winding of relay CHOP to Relay CHOP closes a locking circuit for itself extending from conductor ZMG, make contact of relay CI-IOP, make contact of relay ICHO and winding of relay CHOP to this locking circuit maintaining relay CHOP energized independent of its operating circuit including break contacts of the counting relays.

A circuit is not; closed for operating relay 2Xv extending from (+L make Contact ci. relay ON, make contact of relay CHOP, conductor I2, break Contact of relay LD, conductor I3', break contact of relay ZY and winding of relay 2X to This operation of relay 2X occurs at about the time relay PO is in its right-hand position, consequently when relay,v P3 swings to the left a circuit is closed for operating relay ICB which extends from (-i-), make contact of relay ON, contact of relay PO in its left-hand position, make contact of relay ICHO, make contact of relay CHOP, make contact of relay ICHO, make contact of relay ON, break contact of relay IY and winding of relay ICB to Relay ICB closes an obvious circuit for operating relay ISA and this relay closes the previously described circuit for operating relay ICX. When relay PO next swings to the right, relay ICB is released for operating relay ICI 

